1. Field of the Invention
The present invention relates to an optical mouse and, more particularly, to a position tracking sensor of an optical mouse and method of controlling the same capable of preventing malfunction of the optical mouse and undesired consumption of electrical power which may be generated when the optical mouse is spaced apart from a worktable.
2. Description of the Related Art
An operation state of a position tracking sensor of an optical mouse may be usually divided into an active state and an inactive state according to an operation state of the optical mouse. In the active state, the position tracking sensor continuously detects an image of a worktable such as a mouse pad using light generated by a light source while the light source is maintained in an On state, and then calculates and outputs a value of movement from a change of the detected image. Further, when no change of the detected image is found for a predetermined time, the position tracking sensor is converted from the active state into the inactive state. In the inactive state, the position tracking sensor maintains the light source in an Off state during most of time and periodically turns on the light source to detect the image of the worktable. In this case, the position tracking sensor maintains the inactive state when no change of the detected image is found, but it is converted from the inactive state into the active state when any change of the detected image is found. In this manner, the light source is turned off during most of time while the optical mouse does not move, so that it is possible to reduce consumption of electrical power.
However, in the case of operating as set forth above, there is a possibility of malfunction when the optical mouse is spaced apart from the worktable. In other words, when the optical mouse is spaced apart from the worktable in the inactive state, an image irrelevant to movement of the optical mouse is detected by external light at the position tracking sensor. For this reason, the position tracking sensor may abnormally be converted from the inactive state into the active state. Further, because the image is irrelevant to movement of the optical mouse, the active state may continue to be maintained although the active state must be converted into the inactive state in reality. In both cases, the light source is turned on, so that undesired consumption of electrical power is also generated. Further, in the active state of the both cases, a wrong movement value may be calculated by the image irrelevant to movement of the optical mouse as set forth above.